1. Field of the Invention
The present invention relates to a method of patterning platinum (Pt) layer, and more particularly, to a method of patterning a platinum layer, wherein an etchant used in the patterning process includes at least a chloride-containing gas and at least a fluoride-containing gas.
2. Description of the Prior Art
Along with the development of technology and the improvement of the semiconductor techniques, electronic devices are widely used in modern life. Micro-electro-mechanical system (MEMS) technology is used to fabricate micro mechanical devices by using conventional semiconductor technologies like electroplating, or etching, such that a mechanical component in a micro-meter scale may be formed. The MEMS devices may be applied, for example, in the voltage controlling component in an ink printer, the gyroscope in a car to detect the tilt of the car, the vibration membrane in a microphone to sense a sound, or the micro-heaters in air detectors, chemical detectors, and polymerase chain reaction (PCR) biological chips to provide a local heating function. The MEMS technology which combines the fabrication process of the mechanical and the electronic devices has the advantages of low costs, high performances and high density.
Platinum (Pt), the promising material, can be widely used in very-large-scale integration (VLSI) and MEMS field as electro-thermal, humidity and gas sensor due to its chemical stability and excellent oxidation resistance. Pt also has a high work function and forms a high potential barrier against electron transfer at the interface with the dielectric material, which may suppress leakage current. The MEMS structure made of Pt could be formed through dry etching process accompanied with a photoresist mask; however, some byproducts, such as fence polymer, may be formed at the sides of the formed Pt structure after the dry etching process. The fence polymer is hard to remove, which causes deformations of the formed MEMS structures. Accordingly, a way to pattern the Pt layer to form proper structures without unwanted byproducts to be further used in the MEMS field is an important issue.